On 2012-10-29, Thorsten Bonow <thorsten.bonow at withouthat.org> wrote:
> I'm trying to use "ezunits" to do some calculations, but when using units,
> "solve" looses its capability of solving even simple equations.
'solve' doesn't know anything about units, so from its point of view,
an expression with units is treated the same as some random function or
operator. Some such expressions can be solved by 'solve', some can't.
'solve' can solve variants of the problem you posed if "`" is replaced
by a function or operator. I haven't figured out why it can't solve the
original. In the interest of getting to a solution, my advice is to
solve it symbolically first, then substitute specific values into the
solution:
solve ([A = a*b, b = c*d], [A, b]);
=> [[A = a*c*d,b = c*d]]
subst ([a = 1`m, c = 2`m, d = 3`m], %);
=> [[A = 6 ` m^3,b = 6 ` m^2]]
> Is ezunits mainly for unit conversion or is there a way for
> calculating with units?
I don't know what you have in mind, but ezunits is supposed to be a way
to handle units symbolically. So if you have some such problems to
solve, I would be interested to hear about it. Take a look at the
examples shown by demo(ezunits), especially the one about the speed of
sound toward the end.
best
Robert Dodier